A plasma display panel (hereinafter referred to as a PDP or simply a panel) is a display device with an excellent visibility, large screen, and low-profile, lightweight body. The difference in discharging divides PDPs into two types of the alternating current (AC) type and the direct current (DC) type. In terms of the structure of electrodes, the PDPs fall into the 3-electrode surface discharge type and the opposing discharge type. In recent years, the dominating PDP is the AC type 3-electrode surface discharge PDP by virtue of its easy fabrication and suitability for high resolution.
Generally, the AC type 3-electrode surface discharge PDP contains a front substrate and a back substrate oppositely disposed with each other, and a plurality of discharge cells therebetween. On a front glass plate of the front substrate, scan electrodes and sustain electrodes as display electrodes are arranged in parallel with each other, and over which, a dielectric layer and a protecting layer are formed to cover the display electrodes. On the other hand, on a back glass plate of the back substrate, data electrodes are disposed in a parallel arrangement, and over which, a dielectric layer is formed to cover the electrodes. On the dielectric layer between the data electrodes, a plurality of barrier ribs is formed in parallel with the rows of the data electrodes. Furthermore, a phosphor layer is formed between the barrier ribs and on the surface of the dielectric layer. The front substrate and the back substrate are sealed with each other so that the display electrodes are orthogonal to the data electrodes in the narrow space, i.e., the discharge space, between the two substrates. The discharge space is filled with a discharge gas. For the full color display, in the panel structured above, gas discharge occurring in each discharge cell generates ultraviolet light, by which phosphors responsible for red (R), green (G), and blue (B) are excited to generate visible light of respective colors.
In the typical panel operation, a TV field is divided into a plurality of sub-fields—known as a sub-field method. According to the sub-field method, gray-scale display on the screen is done by combination of the sub-fields to be lit. Each sub-field has a reset period, an address period, and a sustain period.
In the reset period, a reset discharge occurs in all of the discharge cells. The reset discharge erases the previous log of the wall charges for each discharge cell, and then generates the wall charge required for the following addressing operation. The reset discharge also generates charged particles in the discharge space, that is, causes a priming effect. The charged particles trigger a stable address discharge.
In the address period, a scanning pulse is sequentially applied to the scan electrodes, on the other hand, an address pulse that corresponds to the signal carrying the image to be shown is applied to the data electrodes. The application of each pulse selectively generates address discharge between the scan electrodes and the data electrodes, thereby selectively forming the wall charges.
In the successive sustain period, the required number of sustain pulses is applied between the scan electrodes and the sustain electrodes to turn on the cells of which the wall charges have been formed in the previous address discharge.
As described above, the selective address discharge with a high reliability is indispensable to display an image with high quality on the screen. However, a high voltage cannot be used for the address pulse due to constraints of a circuit structure. Furthermore, the phosphor layer formed on the data electrodes is an obstacle to the smooth discharge. These inconveniences are likely to cause delay in discharge in the address discharge. Therefore, great importance is put on generating the priming particles for a reliable address discharge.
The priming effect brought by the discharge, however, is quickly impaired with the passage of time. In the panel operation described above, inconveniences have occurred in the address discharge. Because the address discharge occurs after a long interval from the reset discharge, the charged particles generated in the reset discharge reduce from the number required for the desired priming, thereby encouraging the delayed discharge. The delay in discharge invites an unstable addressing operation, resulting in a poor quality of image display. As another problem, an extended time for the addressing operation, which was intended to provide the addressing operation with stability, has consumed too much time for the address period.
To tackle the problems above, for example, Japanese Patent Non-Publication No. 2002-297091 suggests a panel and a driving method for the same. According to the suggestion, disposing additional electrodes for performing auxiliary discharge generates priming particles, and by which, the delay in discharge is minimized.
In such structured panel, however, due to a perceptible delay in discharge in the auxiliary discharge itself, the delay in the address discharge cannot be desirably shortened, or the small operation margin of the auxiliary discharge can trigger an improper discharge in some panels.
Furthermore, to achieve higher resolution, increasing the number of the scan electrodes of a panel still having a perceptible delay in the address discharge increases the time spent for the address period, which means the lack of time for the sustain period. As a result, the luminance of the panel lowers. At this time, to improve the luminance, increasing the partial pressure of xenon invites further delay in the address discharge, resulting in an unstable addressing operation.
The present invention deals with the problems above. It is therefore the object of the invention to provide a plasma display panel capable of performing a speedy but stable addressing operation.